Re: Possible Threading problem with -CURRENT / MySQL?
From: Julian Elischer (julian_at_elischer.org)
Date: 06/17/04
- Previous message: Kris Kennaway: "Re: (continued) XFree86 problem?"
- In reply to: Robert Watson: "Re: Possible Threading problem with -CURRENT / MySQL?"
- Next in thread: Robert Watson: "Re: Possible Threading problem with -CURRENT / MySQL?"
- Reply: Robert Watson: "Re: Possible Threading problem with -CURRENT / MySQL?"
- Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]
Date: Wed, 16 Jun 2004 18:39:55 -0700 (PDT) To: Robert Watson <rwatson@freebsd.org>
Robert, can you try see if HZ=5000 (up from 100) changes
the performance?
On Wed, 16 Jun 2004, Robert Watson wrote:
>
> On Tue, 15 Jun 2004, Julian Elischer wrote:
>
> > On Mon, 14 Jun 2004, mike wrote:
> >
> > > welcome to our hell. we've been experiencing mysql problems on freebsd 5.x
> > > as well. it sounds like scheduler/threading is to blame but we were not
> > > able to give sufficient or proper motivation to the folks who could
> > > examine this deeper - we even offered $500 cash to whomever stepped up to
> > > help resolve this.
> > >
> > > linux runs almost 2x as fast on the same hardware with no configuring -
> > > and we get nearly the same results running in single CPU mode vs. dual CPU
> > > mode on fbsd... something is definately fubar with the mysql+fbsd5.x
> > > combination.
> >
> > You complained about this some time ago and you have still not responded
> > with the information I suggest..
>
> I sent this to Jeremy privately, since it was just some preliminary
> measurements, but figured I'd send it publically since the results were
> interesting (if tentative, I need to do a lot more work to make them
> useful. There are a number of variables I need to look at including:
>
> - Disabling HTT. A chat with Scott Long this evening suggests that HTT
> may be substantially hurting the test cases given increased IPIs, etc.
> Unfortunately, it looks like I can't easily twiddle HTT without being
> local to the machine, and I'm at home right now (it being 1:30am and
> all). Removing HTT may help substantially with the dip in performance
> in the SMP configuration.
>
> - I'd like to compare against RELENG_4 and a recent Linux kernel.
> Unfortunately, the box is configured for neither right now.
>
> - I need to try twiddling schedulers -- this was with SCHED_ULE, and I'd
> like to try SCHED_4BSD.
>
> - This was without adaptive mutexes, which seem to be helpful for others,
> so I should give them a try.
>
> I don't have any amd64 hardware, so I don't know what if any role it will
> play in the results. The performance drop observed in the report appears
> to be on amd64 (I may have misread).
>
> Robert N M Watson FreeBSD Core Team, TrustedBSD Projects
> robert@fledge.watson.org Senior Research Scientist, McAfee Research
>
>
> ----
> Date: Wed, 16 Jun 2004 01:15:39 -0400 (EDT)
> From: Robert Watson <rwatson@FreeBSD.org>
> To: JG <amd64list@jpgsworld.com>
> Subject: Re: Possible Threading problem with -CURRENT / MySQL?
>
>
> On Tue, 15 Jun 2004, JG wrote:
>
> > Fwiw, it has to be something that was committed between May 18th and
> > yesterday. ~May 18th was the last time I built -CURRENT during my last
> > round of testing and I did not have any of these problems. Then someone
> > emailed me recently and said there were some commits that might effect
> > the outcome of the mysql benchmarks.
>
> Ok, so these results are on a dual-processor XEON + hyperthreads, so four
> logical processors. I used two dates off CVS, 20040515 and 20040615. I
> also benchmarked my netperf branch. I don't have RELENG_4 on the box, but
> might be able to load RELENG_4 on it later this week. In each case, I
> took ten samples, dropped the first value as getting into the cache, and
> took the mean of the rest. For this test, I used the select test; I'll
> try the other smack query set tomorrow. In each case, I ran with "10
> 1000" as the arguments to the test. I used the default threading
> configuration in -CURRENT, which is libpthread (libkse).
>
> Mean Stdev
> 20040515-UP 4752.27 14.63
> 20040515-SMP 2550.35 19.23
>
> 20040615-UP 4898.71 22.39
> 20040615-SMP 2666.93 32.01
>
> Netperf-UP-giant 4902.41 14.3
> Netperf-SMP-giant 2566.18 16.83
> Netperf-UP-mpsafe 4799.35 22.04
> Netperf-SMP-mpsafe 3022.51 18.06
>
> Unfortunately, I can't turn off HTT remotely, and I'm guessing it damages
> the SMP numbers a fair amount due to additional IPIs without benefit.
> However, the numbers basically suggest that on my hardware, the UP
> configuration is marginally faster than it was last month, and that if you
> throw in the netperf branch, the SMP case is a moderate amount faster.
> This suggests that either I'm just lucky, or that the performance loss
> might be specific to the amd64 version of FreeBSD. I'm going to run some
> more numbers tomorrow and try to post something more rigorous to the
> -threads list.
>
> I don't have RELENG_4 on the box or Linux on the box, but I may get a
> chance to later this week.
>
> Robert N M Watson FreeBSD Core Team, TrustedBSD Projects
> robert@fledge.watson.org Senior Research Scientist, McAfee Research
>
>
>
_______________________________________________
freebsd-current@freebsd.org mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-current
To unsubscribe, send any mail to "freebsd-current-unsubscribe@freebsd.org"
- Previous message: Kris Kennaway: "Re: (continued) XFree86 problem?"
- In reply to: Robert Watson: "Re: Possible Threading problem with -CURRENT / MySQL?"
- Next in thread: Robert Watson: "Re: Possible Threading problem with -CURRENT / MySQL?"
- Reply: Robert Watson: "Re: Possible Threading problem with -CURRENT / MySQL?"
- Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]
Relevant Pages
|
|
